Same thing here my morning cortisol is high a bit like yours. I wake up feeling like hell, and I am really tired. I had 3 cortisol test done. 1 2-3 years ago high in the morning a bit low the rest of the day (similar to yours) and 2 cortisol done this year that shows a cortisol that is in the upper limit of the range pointing towards high cortisol rater then low.
All this to say that this year is the worst I have felt since having AF and my cortisol look more normal then it was before.
AF/CFS , environmental disease , etc. Are more then just a cortisol test. The thyroid , nervous system endocrine system are all at play here.
I would suggest you really start doing some intense relaxation everyday asap and start supplementing right. Also you should listen to your body and avoid crashing and symptoms. if you are not feeling well something is not right , the more you push the more harm you cause. Trust me I have been living non stop with this for 7-8 years and it gradually get worse if you push yourself and fail to listen. Might slow down while you are ahead.